Mechanical apparatus for micrometric tuning of piano strings



O. MADQNNA MECHANICAL APPARATUS FOR MICROMETRIC TUNING OF PIANO STRINGS Filed March 24. 1954 MECHANICAL APPARATUS FOR MICROMETRIC TUNING OF PIANO STRINGS ron zo Madonna, Lecce, Italy Application March 24, 1954, Serial No. 418,328

Claims priority, application Italy April 11, 1953 2 Claims. (Cl. 84-204) In the art of building pianos, the holding firmly in place of the pegs, on which the strings are wound, has always been one of the most important problems and is still receiving attention and investigation by builders of these instruments. In the stability or firmness of the pegs resides the stability of the tuning of the instrument, and this explains the importance of this technical detail. The system has been improved by the use of a thoroughly seasoned wood, by a simple and multiple sheathing having crossed rows and even by applying an armor plating to the frame. In effect, everything'has been done and is being done with a view of holding firmly in place the pegs, but a perfect stability has never been achieved.

The object of the present .invention is to provide a mechanical apparatus which permits elimination of the wooden chest and the pegs in pianos and similar instruments and enables tuning, even micrometrical tuning, of the strings being simultaneously performed, so as to ensure a perfect stability .of the tune.

The mechanical metal apparatus according to the invention is formed from a support of solid or resistant material, such as steel, to which a cylinder is applied, around which the string is wound to obtain the first tension.

The said support, which rests on a metal plate, is shaped screw provided with a head, preferably of polygonal section and an overhanging disc, which screw is introduced into the supporting metal plate and causes said support to shift towards this plate. The said cylinder is applied to the support through an external projection provided on the support betweenits lower fork and upper opening, which projection will be called hereinafter an abutment, with a circular rim having saw teeth adapted to exactly contact with corresponding teeth provided on the cylin der, and with a recess which is occupied by a screw passing likewise through the inner hole of said cylinder.

A modification of the invention consists in that the cylinder, resting on the abutment of the support, is eliminated, thus reducing the manufacture to the projection only, which overhangs the metal plate and is provided with a transverse hole and a slot extending from the top downwards, the string, which is secured to the support, being placed into said transverse hole and said vertical slot.

Another modification of the invention consists in that on the abutment, instead of in the slot, a threaded hollow extension and a hole may be provided for the passage of the string, which hole in the abutment extends from the bottom to the top. By placing a screw inside the said extension of the abutment, the top end of this screw extends sufficiently far to bear on the inner non-apertured wall of the abutment and to exert a pressure against the string, so as to lock it to the support. A third modification of the present invention is provided by introducing a drum provided with a toothed wheel, having preferablyhelical teeth and engaging with a-worm screw in 'place of the support mentioned hereinbefore.

Patented Dec. 22, -9

A still further modification is represented by such means as are used to support both the worm screw and the toothed wheel.

Whatever the specific application of the aforesaid modifications may be, the operation of the mechanism is always based on the same principle: to obtain a first approximate tension of the strings through action exerted upon the abutment of the support, and then to obtain the definite tension by operating the screw which causes the upper portion of said support to approach the bearing metal plate.

In the particular case of the last-mentioned modification of the invention, the tension of the strings is entirely based on the operation of the worm screw which will cause the toothed wheel to rotate, to whose axis the string to be tuned is secured, thus eliminating the previous step of mechanical pull.

The invention is illustrated by way of example only, without any limitation, on the accompanying drawings, in which:

Fig. 1 is a side view, partially in section, of the assembly without the wooden chest and the pegs and permitting of a micrometric tuning being performed;

Fig. 2 shows a front view of the support;

Fig. 3 is a side view, partially in section, embodying the modification without the cylinder shown in Fig. l

The support of Fig. 4 is a front view of Fig. 3;

Fig. 5 is a side view, partially in section, of a second modification of Fig. 1;

Fig. 6 is a front view of Fig. 5;

Fig. 7 is a side view, partially in section, of an assembly without the support shown in Fig. l and the following figures, according to another modification of the invention; i

Fig. 8 is afront view of Fig. 7;

Fig. 9 shows a detail front view of the toothed wheel with the respective drum, and

Fig. 10 shows the development of the supporting member of the toothed wheel and the worm screw.

Referring to said drawings, to the iron plate 1 of the piano, or like instrument, a support 2 is applied by means of its lower fork 5, which enters into the bearing 4 secured to said plate, and a screw 3 which serves both to prevent the support from shifting laterally and to act as a tie rod for said support. It will be observed hereinafter that this screw 3 in determined conditions may also have supporting functions. The support 2 is formed in such a way as to have a fiat surface on the side facing the metal plate 1, which extends to the lower fork 5, whereas the surface opposite the metal plate has its upper portion rounded off to offer less friction to the tie rod screw 3 which passes through the window 14 of the support 2, the said support having a lower circular hollow portion 11, the rim of which is provided with teeth 15. The screw 3 has a square head 6 and is provided with a collar 7 which bears on the rounded off portion of support 2, onto which the pressure of the tie rod screw 3 is transmitted. A cylinder or drum 8, provided with a square head 6, is applied to the toothed rim. This square head may have the same size as the head of screw 3, so that it will be possible to operate them with the same suitably shaped spanner. The hollow cylinder or drum 8, on the side opposite to head 6, is provided a toothed rim having the same size as the toothed rim provided on support 2. Additionally, the said cylinder, which is fastened to the support'by means of a screw, is provided with a transverse hole, into which the string 9 is introduced prior to the start of the winding thereof around said cylinder 8. To the metal plate 1, a compressor 10 is also applied by means of a screw 12 which, upon being operated, will cause string 9 to bear upon the main key.

Figs. 3 and 4 show the support 2 resting on plate 1,

- 2,917,961 s I t and the omission of the cylinder 8 shown in Fig. 1, the toothed rim 15 being converted into an abutment 18 provided with a transverse hole 16. The tensioned string 9 passes through a vertical slot in the abutment 18 and is wound around said abutment.

Figs. and 6 show another modification in which the hollow abutment is extended and provided with a screw 20, the latter being introduced into said recess of said abutment far enough to cause the string 9, passing through the abutment across vertical holes provided therein, to reach the wall of the support and to be locked against the same.

Fig. 7 shows another form of the invention, according to which the iron plate 1 of the piano, or like instrument, has a frame 21 applied thereto as by means of screw 3, representing the assembly which eliminates the chest and the pegs, and permitting micrometrical tuning. This frame 21 is provided with a worm screw 23 and a toothed wheel 24 meshing with said worm screw. This worm screw is formed on a pin 25, whose free end 26 terminates in a polygonal or square section. In this modification, the screw 3 merely acts as a support for the frame, and replaces the support shown in the previous figures, thus fastening the frame to the metal plate without exerting any pulling action. The teeth of toothed wheel 24 are preferably of helical shape and arched according to the radius of worm screw 23. As shown in Fig. 8, this wheel is mounted on or formed in a drum 22 provided with a hole 16 into which the string is introduced.

By causing the worm screw 23 to rotate by means of a spanner applied to the end 26 of pin 25, the toothed wheel 24 is also caused to rotate, so as to wind the string upon drum 22.

These members forming the system of micrometric adjustment according to the modification shown in Fig. 8, bear upon a support 2 as illustrated in detail in Fig. 10. This support may be obtained by any suitable system, for example by casting, or, as shown in the aforesaid figure, it may be formed from a suitably shaped and embossed plate which may be bent as indicated by dotted lines in said Fig. 10. The support or plate 2 is provided with two recesses 27 in which the drum 22 is housed. At the upper part and facing the recesses 27 two recesses 28 are provided which form a support for the pin 25 towards its free end 26. In the central portion of the plate or support 2 two holes 29 and 30 are provided, the hole 29 forming the housing for the locking screw 3 of support 2 to the plate 1 of the instrument, whereas the hole 30 permits the passage of pin 25. As shown in section in Fig. 7, the hole 30 is embossed from the inside towards the outside, so as to form a housing for the base of pin 25.

The assembly and operation of the apparatus according to the invention are extremely easy and will be apparent both from the above specification and from what will be stated hereinafter.

The main function of the screw 3 is to act as a tie rod for the support 2, to cause said screw, by its being shifted through screwing action in the plate, to approach said support towards said plate 1, so as to permit a micrometric tuning of the strings of the instrument. There may, however, be no bearing fork 5 or hearing 4, in which case the screw 3, besides serving as a tie rod, will act also as a bearing for the support itself.

Whatever may be the system employed for obtaining the tension and the holding firmly in place of the strings to be tuned, the first step resides in the fixing of the string to the abutment of the support, the string thus receiving a first tension. By a second step and through the action of the tie, rod screw 3, the shifting caused on the support will permit of micrometric tuning being performed.

. As far as concerns Fig. 1, itis to be stated that the cylinder 8 applied to support 2, owing to the two toothed rims being approached, is maintained integral with the support 2 by means of a screw, but with the possibility.

, 4 of being shifted axially, with respect to the toothed rim 15 of the abutment, a distance corresponding to the sum of the height of the teeth of the two rims, which teeth are of uniform shape and are associated in such a way as to permit a sliding motion in only one direction and never in the other direction.

Referring again to Fig. 7, it is to be borne in mind that, upon having bent the supporting plate 2, the toothed wheel 24 is mounted in such a way as to cause the grooves 31 of the drum 22, shown in Fig. 9, to engage with the edges of the single recesses 27. At the same time, through the hole 30 the pin 25 with its endless thread 23 is caused to enter in such a way as to bring the enlarged base of said pin 25 to the same level as that of the outer portion of the bent support 2 which will bear against the iron plate 1 of the instrument. When introducing the pin 25 into the hole 3%, the recesses 28 will be housed within an appropriate groove provided on the pin 25, so as to cause the whole assembly of the toothed wheel 24 and the worm screw 23 to be locked. The support to the plate is obtained by introducing the screw 3 through the hole 29. Thereupon the string 9 is introduced into the hole 16 of the drum 22 carrying the toothed wheel 24 and, by operating the polygonal or square head 6 of pin 25 by a suitable spanner, the worm screw 23 and, consequently, the toothed wheel 24 are caused to rotate, so as to tension and then to adjust the string for the final tuning.

The advantages of the present invention are apparent. Of particular importance is the great ease in building and assembling the several parts Without the need. of performing difficult operations or having recourse to other accessories to obtain the movement necessary for tensioning the strings, a perfect stability of the tune being assured and the operation of tuning taking place in a very smooth manner.

What I claim is:

1. Means for micrometrically tuning pianos and like stringed musical instruments, comprising a piano plate, support means secured to the piano plate, a worm screw mounted rotatably in such support and a toothed wheel having teeth meshing with said worm screw and turned thereby, the said toothed wheel being positively locked in the position to which it is turned, said support being formed from a shaped plate having a fiat base with a struck-up portion and upstanding recessed sides to receive the worm screw and toothed wheel and having an aperture in the flat base through which it is secured to the piano plate, a pin carrying said worm screw and having an enlarged base at one end terminating close to but out of contact with said piano plate and held by said struck-up portion against withdrawal from said base and a polygonal section at its other end and a groove adjacent its said other end for the engagement therein of portions of said support plate, the base at the opposite end of the said pin being disposed for rotatable movement in the plane of the external face of the piano plate, a drum on which the toothed wheel is mounted, said drum being provided with a hole for anchoring one end of a piano string, which drum has grooves adjacent its ends for engaging cornplementarily shaped portions of the support plate, and the teeth of the toothed wheel being concave to conform to the curvature of the worm screw.

2. Means for micrometrically tuning pianos and like stringed musical instruments, comprising a piano plate, support means secured to the piano plate, a worm screw mounted rotatably in such support and a toothed wheel having teeth meshing with said worm screw and turned thereby, the said toothed wheel being positively locked in the position to which it is turned, said support being formed from a shaped plate having a fiat base with a struck-up portion and upstanding recessed sides to receive the worm screw and toothed wheel and having an aperture in the flat base through which it is secured to the piano plate, a pin carrying said worm screw and having an enlarged base at one end terminating close to but out of contact with said piano plate and held by said struck-up portion against withdrawal from said base and a polygonal section at its other end and a groove adjacent its said other end for the engagement therein of portions of said support plate, the base at the opposite end of the said pin being disposed for rotatable movement in the plane of the external-face of the piano plate, a drum on which the toothed wheel is mounted, said drum being provided with a hole for anchoring one end of a piano string, which drum has grooves adjacent its ends for engaging complementarily shaped portions of the support plate, and the teeth of the toothed wheel being concave to conform to the curvature of the worm screw, the shaped plate, prior to being fabricated to final form for attachment to the piano plate being flat and having a central panel portion with two spaced vertically aligned holes one of which receives a locking screw for making said attachment and the other of which provides a passage for said pin, portions extending laterally on each side of the central portion and each having a recess for housing said drum and defined by tapering in-curved projections terminating short of said lateral portions, and lateral ends each of which is provided with a semi-circular recess facing a recess in one of the lateral portions but outwardly displaced with respect thereto, said recessed ends, in the final fabricated form of the shaped plate abutting each other in registry to form a bearing for said pin.

References Cited in the file of this patent UNITED STATES PATENTS 104,417 Branig June 21, 1870 360,409 Berner Apr. 5, 1887 1,026,228 Severy et a1. May 14, 1912 FOREIGN PATENTS 106,558 France Jan. 26, 1875 13,036 Great Britain Oct. 13, 1886 130,589 Germany Sept. 4, 1901 22,631 Finland July 22, 1948 

